Is GeyserMC supported?

Answer to this frequently asked question.

Yes, it is, including GeyserMC Floodgate. No additional configuration is required.

If you are using IP-whitelist, make sure to whitelist the GeyserMC server address and enable forward-hostname as defined here.

If you can't do so, you may need to whitelist the IP GeyserMC server used to connect to BungeeCord.